The major goal of this proposed research is control of hemoglobin synthesis, with emphasis on development of methods for augmenting net synthesis of fetal-type hemoglobins. Although the ultimate clinical goal is alleviation of human diseases of hemoglobin, the research program deals with basic aspects of erythroid maturation, of hemoglobin ontogeny, and of hemoglobin synthess in general. The animal species to be used in these studies is hamster, the ontogeny of whose hemoglobins has been established in this laboratory. Hamster possess a fetal hemoglobin persisting into adult life. Attempts to alter relative rates of synthesis of hamster individual hemoglobins will involve manipulations of gene function through, for example, trials with appropriate hormonal stimuli. These attempts will be directed at cell processes taking place both during erythroid maturation and during the period of time of maximum ontogenic change in hemoglobin relative proportions.